PRO2004.1
   A pushbutton switch, attached to a 4060 CMOS 14 bit binary counter IC,
selects one of the 16 groups.  The 4 counter output leads are used to select
the high order 4 bits of the HM62256.  The new group select pushbutton switch
is mounted on the front panel, in place of the headphone jack.

   How can you tell which group you are in?  A specially programmed  EPROM
(type 2716, 2532, or 2732) is addressed by the ouput of the counter.  The
EPROM output is connected to a 7 segment LED readout, mounted in place of the
Sound Squelch pushbutton.  The readout indicates groups 0, 1, 2, 3, 4, 5, 6,
7, 8, 9, A, B, C, D, E, and F.

   [Note: If I were to expand the memory in my PRO-2004,  I would use just the
new HM62256 memory IC and a BCD switch instead of the pushbutton.  This would
eliminate two of the three ICs, and the 7 segment readout.  Sorry, I cannot
provide further information, nor a reference, as the sheets sent to me
contained no name or address. - Bob
   Parnass] Bob Parnass AJ9S